Thermodynamic And Kinetic Studies Of Protein Structure A

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This laboratory is interested in the relationship among protein sequence, structure and the mechanisms of protein folding and enzymic reactions. (i) Secondary Structure of Insoluble Proteins. The structure of a protein in solution is readily estimated by mathematical analysis of its circular dichroism (CD)spectrum. Proteins implicated in prion diseases are insoluble and must be studied as thin films. Under these circumstances, protein concentration, which is usually necessary for quantification and analysis of CD data cannot be determined. We have shown a concentration independent method of structure determination, which involves measurement and deconvolution of the protein's "g-factor" spectrum, which is the ratio of a samples CD and absorbance spectra. (ii) Structure of Cystathionine beta Synthase (with Dr. Edith Wilson Miles and coworkers, LBG) We are investigating the conformational states of the tryptophan synthase alpha2-beta2 complex and their relevance in the enzymatic mechanism of the protein. (iii) Structure of Mammalian Sulphotransferases. (with Dr. D. Marshall and Dr. W.B. Jakoby, LBM) The enzymatic activity of a phenol sulphotransferase, from rat liver, has been shown to be regulated by reversible oxidation/reduction of a conserved specific cysteine residue by physiological concentrations of glutathione. Oxdation of cysteine residue 66 inhibits the physiological activity of the enzyme by very tight substrate inhibition. This mechanism may be important under conditions of oxidative stress to the liver. (iv) Structure of Rotavirus protein NSP2 (with Dr. Peter Schuck, ORS, OD and Dr. Z. Taraporewala, LID, NIAID) This protein is a component of the virus' replication apparatus, interacting with RNA and nucleotides. We are studying its structure and the changes induced by interaction with ligands.